6  2  7./ 

: ril  C  egress,  i  HOUSE  OF  life WIESESTATl VES.  (  Ex.  Doe. 

u  “  ”  - 

'  ^  > 


\tsi 

.4- 

■Q 


/r'  '•  # 

*  1  1 

\  No.  58. 

f  , . 

fiP'C&T  OF 

J  l 

Mi.  im  '  '  ' 

A 

•  l  '■  >1  F 

mission. 

'Xt 

r  • 

3  T  T  L 

» 

r  sf  C 

FROM  - 

v  A 

#  * 

■  7 

■■■'  4 

o  r  U 

ft  L  7  A  R  Y 

c 

W  A  R . 

TRANSMITTING 

The  prelim l nary  report  of  the  Mississippi  Hirer  Commission. 


March  10,  1880. — Referred  to  tlie  Committee  on  Commerce  and  ordered  to  be  printed. 


War  Department, 
Washington  City ,  March  10,  1880. 

The  Secretary  of  War  has  the  honor  to  transmit  to  Congress,  in  com¬ 
pliance  with  the  provisions  of  the  act  approved  June  28,  1879  (chap.  43, 
Aimphlet  Laws,  page  38),  a  preliminary  or  partial  report  of  the  Mis¬ 
sissippi  Eiver  Commission,  with  the  papers  accompanying  the  same; 
also  a  minority  report  of  two  members  of  the  Commission. 

Eespect fully  submitted. 

ALEK.  EAMSEY, 

Secretary  of  War. 

The  Speaker 

of  the  House  of  Representatives. 


Tiie  Mississippi  Eiver  Commission, 

President’s  Office,  Army  Building, 

33  West  Houston  Street, 

Kew  Yorlc ,  March  6,  1880. 

Sir:  I  have  the  honor  to  transmit  herewith  a  preliminary  or  prartial 
•eport  of  the  Mississippi  Eiver  Commission.  It  is  expected  that  the  two 
uembers  of  the  Commission — Geueral  Comstock  and  Mr.  Harrison — who 
lave  withheld  their  signatures  from  the  report  will  submit  separate 
tatements,  embodying  individual  dissenting  opinions,  upon  the  several 
ubjects  discussed  therein.  When  these  are  received  they  will  be  for¬ 
warded  without  delay,  in  order  that  they  may  take  their  appropriate 
lace  as  appendices  to  the  report. 

The  following  papers  are  hereunto  appended,  viz.: 

I  1.  A  financial  statement  made  by  Lieut.  Smith  S.  Leach,  Corps  of  En- 
Lueers,  the  disbursing  officer  of  the  Commission,  showing  the  disburse- 


REPORT  OF  MISSISSIPPI  RIVER  COMMISSION. 


meuts  made  and  liabilities  incurred  to  February  1G,  1880.  It  will  be  ' 
seen  from  the  statement  that  the  whole  amount  appropriated  will  be 
expended  by  the  close  of  the  current  fiscal  year  in  making  the  surveys  . 
and  examinations  deemed  requisite  by  the  Commission. 

2.  A  Coast  Survey  chart  of  the  “Mississippi  River  from  the  Passes  to  • 
Grand  Prairie,  Louisiana,?’ 

It  is  understood  from  the  superintendent  of  the  Coast  and  Geodetic 
Survey  that  the  engraved  plate  of  this  chart  will  be  placed  at  the  dis¬ 
posal  of  the  Public  Printer,  so  that  its  reproduction  will  be  unnecessary  A 
Very  respectfully,  vour  obedient  servant, 

Q.  A.  GILLMORE, 

Lieutenant- Colonel  of  Engineers,  Bt.  Maj.  Gen.,  U.  S.  A., 

President  Mississippi  Elver  Commission. 

Hon.  Alexander  Ramsey, 

{Secretary  of  War ,  Washington ,  1).  C. 


[Indorsement.] 


Office  Chief  of  Engineers,  U.  S.  Army, 

March  8,  1880. 

Respectfully  forwarded  to  the  honorable  the  Secretary  of  War. 

II.  G.  WRIGHT, 

Chief  of  Engineers,  Brig.  &  B-v't  Maj.  Gen. 


REPORT. 

Washington,  D.  C.,  February  17,  1880. 

Sir:  The  Mississippi  River  Commission,  constituted  under  an  act  of  1 
Congress  approved  June  28,  1870,  respectfully  submit  the  following 
partial  report : 

The  work  assigned  to  the  Commission  was — 

First.  To  direct  and  complete  such  surveys  of  the  Mississippi  River 
between  the  Head  of  the  Passes,  near  its  mouth  and  its  headwaters,  as 
were  then  in  progress;  and  to  make  such  additional  surveys  and  ex¬ 
aminations  of  said  river  and  its  tributaries  as  might  by  it  be  deemed 
necessary. 

Second.  To  take  into  consideration  and  mature  such  plan  or  plans  as 
will  correct,  permanently  locate,  and  deepen  the  channel,  and  protect 
the  banks  of  the  Mississippi  River;  improve  and  give  safety  and  ease 
to  the  navigation  thereof;  prevent  destructive  floods,  and  promote  and 
facilitate  commerce  and  the  postal  service;  and  with  such  plans  to  pre¬ 
pare  and  submit  estimates  of  the  cost  of  executing  the  work. 

Third.  To  report  specifically  upon  the  practicability,  feasibility,  and 
probable  cost  of  the  plans  known  as  the  jetty  system,  the  levee  system, 
and  the  outlet  system. 

By  section  5  of  the  act  authority  was  given  to  the  Commission,  prior  ] 
to  the  completion  of  all  the  surveys  and  examinations,  to  prepare  and 
submit  plans  and  estimates  of  cost  for  such  immediate  works  as  in  the 
judgment  of  the  Commission  may  constitute  a  part  of  the  general  system 
of  works  contemplated. 

The  Commission  met  for  organization  in  the  city  of  Washington  on 
the  19th  day  of  August,  all  the  members  being  present,  and  immediately 
upon  its  organization  took  into  consideration  the  surveys  of  the  river 


REPORT  OF  MISSISSIPPI  RIVER  COMMISSION.  3 

ilready  u in  progress,”  and  Usuch  additional  surveys,  examinations ,  and 
investigations ,  topographical ,  hydrographical ,  and  hydrometrical ,v  as 
‘ciseemed  necessary  to  carry  out  the  objects  of  the  act  of  Congress  estab¬ 
lishing  the  Commission. 

al  It  was  found  that  the  portion  of  the  river  lying  above  the  mouth  of 
tp<jlie  Ohio  had  been  essentially  covered  by  the  several  shore-line  surveys 
ylMready  completed,  or  drawing  to  a  close,  so  that  the  attention  of  the 
^Commission  was  directed  more  especially  to  the  lower  river  between 
^t(Oairo  and  the  Head  of  the  Passes.  This  portion  of  the  river,  measuring 
ibout  1,100  miles  along  the  channel,  had  been  the  scene  of  numerous 
Jadetached  surveys,  the  data  from  which  will  be  available  notwithstand¬ 
ing  the  intervals  of  time  that  they  cover ;  and  in  providing  for  the  con¬ 
nection  and  extension  of  these,  the  Commission  decided  to  so  arrange 
girlie  work  of  the  present  fiscal  year  that  the  information  immediately 
jWrequired  should  be  obtained  by  systematic  methods,  useful  not  only  to 
jtlihe  proximate  ends  in  view,  but  in  connection  with  the  wider  range  of 
■m  nquiry  that  must  ultimately  be  necessary. 

i<;  it  was  considered  important  that  the  triangulation,  so  essential  in 
jthocating  the  river,  however  limited  the  field  of  practical  operations  of 
•tommediate  improvement  might  be,  should  be  so  executed  and  per- 
^fnauently  marked  that  it  would  furnish  the  basis  of  future  surveys. 
b(  It  was  therefore  decided  that  a  line  of  secondary  triangulation  should 
its  triangles  closing  within  G  seconds. 

For  the  present,  however,  it  was  deemed  desirable  to  execute  no  de¬ 
railed  or  widely-extended  topography,  but  to  develop  as  rapidly  as 
sljpossible  the  shore  lines  and  the  forms  of  the  liver  bed. 

^  It  was  furthermore  decided  that  physical  inquiries  extending  to  all 
the  recognized  phenomena  likely  to  have  a  bearing  upon  problems  of  im- 
Srovement  should  be  instituted  at  once,  and  that  they  should  be  based 
ipon  the  experience  of  predecessors  who  had  already  made  much  pro¬ 
gress  in  these  studies. 

Provision  was  made  for  running  lines  of  precise  levels  along  the  river 
auk  and  for  maintaining  and  increasing  the  number  of  the  stations  at 
hich  the  elevations  of  the  river  are  recorded,  so  as  to  trace  in  future 
he  progress  of  floods  and  the  larger  features  of  the  river  slopes,  witli- 
jtl|>ut,  it  is  hoped,  any  further  interruption. 

Provision  was  also  made  for  physical  examinations  of  selected  reaches 
f  the  river,  distant  from  each  other,  but  presenting  locally  and  rela- 
ively  the  most  widely-contrasted  elements  of  width,  depth,  and  curva- 


i  oeruu, 
b' 


£ 

i® 

t 1 


t 


s 

ijure;.  that  the  conditions  most  favorable  and  those  most  inimical  to 
pliavigation  might  thus  be  traced  back  to  their  causes  inductively, 
ol  At  these  early  meetings  resolutions  were  adopted  embodying  the 
bpense  of  the  Commission  as  to  the  extent  and  character  of  the  surveys 
equired,  and  the  committee  composed  of  a  majority  of  the  members 
vas  appointed  to  carry  out  the  views  thus  recorded. 

Inquiries  were  made  of  the  Secretary  of  War  and  of  the  Secretary 
t*)f  the  Treasury  as  to  the  aid  they  could  render  in  these  surveys,  free  of 
vl^xpense  to  this  Commission,  and  the  committee  on  surveys  was  author¬ 
ized,  after  the  receipt  of  replies  to  the  above  inquiries,  to  direct  the 


iP 

i! 


a 


i  *i 


secretary  of  the  Commission  to  employ  the  necessary  persons,  and  make 
lall  purchases  of  instruments,  materials,  and  outfit  needed  to  carry  out 
[the  provisions  of  the  resolutions  already  adopted  as  to  surveys,  &c.,  to 
>e  made  at  once. 

The  surveys  thus  instituted  are  being  executed  under  direction  of 
:his  Commission  in  part  by  its  employes  and  in  part  by  parties  and 
Vessels  of  the  Coast  and  Geodetic  Survey;  detailed  under  section  3  of 


1 


REPORT  OF  MISSISSIPPI  RIVER  COMMISSION. 


e 


the  act;  the  former  moving  from  Cairo  southward,  the  latter  working  in 

the  lower  part  of  the  river.  .  1$ 

The  continual  prevalence  of  yellow  fever  at  several  points  on  t  • 

lower  river  until  late  in  the  fall  prevented  these  parties  from  beginning 

their  work  as  soon  as  was  expected.  1i7,  0 

The  following  estimates  of  the  extent  of  river  completed  01  like  y 
be  covered  during  the  present  season  are  based  upon  the  rate  ot  progress, 
furnished  in  the  schedule  drawn  up  by  the  Secretary  of  the  Commission, 


be  covered  during  me  preseut  aic  — y  * — ~ 0 

furnished  in  the  schedule  drawn  up  by  the  Secretary  of  the  Commission, 
and  in  the  report  of  the  Superintendent  of  the  Coast  and  Geodetic  ^ 

^Gauaes  —The  gauges  along  the  river  between  Cairo  and  New  Orleans 
were  increased  in  number  to  20,  and  more  recently  others  have  been 
added  between  Cairo  and  Saint  Louis,  so  that  the  elevations  of  the  m  ei 
surface  are  now  recorded  daily  at  intervals  ot  about  50  miles. 

The  zeroes  of  these  gauges  are  to  be  referred  to  a  common  plane  of 
re/erencJ  by  the  lines  of  precise  levels  to  be  described  hereafter  in  the^ 

0rATrialgllaUonS—0(  the  1,100  miles  of  river  lying  between  Cairo  and 
the  Head  of  the  Passes,  the  triangulation  of  past  years,  executed  by  1 1 
oovernmeut,  amounted  in  all  to  about  407  miles,  comprising  the  progress 
work  of  the  Coast  and  Geodetic  Survey,  as  well  as  the  surveys  made 

by  the  United  States  Corps  of  Engineers. 

Of  the  employes  of  the  Commission,  three  double  parties,  now  m  the 
field  are  engaged  upon  triangulation.  This  work,  inclusive  of  about  lb 
miles  previously  executed, has  already  reached  Memphis;  and, as  be  ow 
this  point  about  85  miles  of  work  previously  executed  will  be  met  with, 
it  is  anticipated  that  the  parties  will  reach  the  mouth  of  \\  hite  Pvi\ei, 

420  miles  below  Cairo,  by  the  1st  of  April. 

The  trigonometrical  points  established  by  these  parties  are  to  be  r  - 
ferred  to  permanent  marks  beyond  the  erosions  ot  the  river,  by  the  topo- 

frranhical  party  following  them.  ,  1 

Four  single  triangulation  parties  have  been  placed  on  the  river,  under 
this  Commission,  by  the  Superintendent  of  the  Coast  and  Geodetic  Sum 
vev  Mr  C  P.  Patterson ;  and  these  have  been  located  by  the  board 
with  a  view  to  connect  the  isolated  fields  of  work  which  now  rest  upon, 

8ej\lr.  Patterson  expects,  with  the  appropriation  made  by  Congress  for 
the  work  under  his  superintendence,  together  with  an  allotment  from 
the  funds  of  this  Commission,  to  execute 300  miles  ot  triangulation  dur- 
i u  o’  the  present  fiscal  year,  and  make  the  chain  of  geographical  positions 
fomnlete  from  the  Gulf  of  Mexico  to  Providence,  about  oOO  miles. 

As  these  parties  were  not  to  be  immediately  followed  by  topo- 
oranhical  surveyors,  it  was  deemed  advisable  to  require  ot  them  the  es- 
fablishment  ot  reference  marks,  which  has  rendered  their  progress 

slower  than  it  otherwise  would  have  been.  . 

At  the  request  of  the  Commission,  the  Superintendent  of  the  Coast 
ami  Geodetic  Survey  has  measured  a  base  line  in  the  vicinity  ot  Cotton 
wood  Point,  120  miles  below  Cairo,  to  be  used  in  connection  with  the 

triangulation  executed  by  t  he  employes  of  the  board. 

Topography  and  Hydrography.— These  have  been  combined  in  the 
operations  of  one  party,  having  three  divisions,  composed  ot  employe. 

the  Commission.  One  of  these  divisions  develops  the  shore  line  o. 
tlie  actual  river  with  its  banks,  tow-heads,  chutes,  islands,  & e.,  as  wel 
as  levees  when  not  more  than  a  half  mile  back  from  tbe  water ;  auot  lei 
follows  with  levels,  giving  the  elevations  of  banks,  water-surtaces,  cross 
Sons  of  levees,  &c. ;  while  the  third  division  sounds  out  the  bed  o 


f 


1 


REPORT  OF  MISSISSIPPI  RIVER  COMMISSION.  5 

r 

‘tlib  stream  in  connection  with  the  levelings,  so  as  to  complete  the  normal 
,cr)ss-sections  of  the  river  and  its  approaches  about  every  half  mile.  All 
itbU  work  rests  upon  the  preceding  triangulation,  and  the  topographers, 
they  pass  the  triangulation  stations,  are  required  to  refer  them  to 
tp<rmanent  marks  already  mentioned.  These  marks  are  placed  about 
.tlree  miles  apart,  measured  along  the  general  course  of  the  river,  and 
^ir  pairs  on  either  side,  the  one  nearest  the  river  bank  being  so  placed  as 
be  sure  to  remain  undisturbed  for  at  least  twenty  years. 

,  The  present  work  will  not  furnish  a  detailed  map  showing  the  char¬ 
ter  and  elevation  of  the  swamp  and  bottom  lands  lying  far  back  from 
jte  actual  lines  of  the  river,  but  the  necessity  of  more  elaborate  maps  as 
Aticipated,  and  these  marks  are  to  secure  the  full  advantage  of  all  tri- 
^igulation  executed  this  season  as  the  basis  of  future  topographical 
ork  wherever  the  trigonometrical  points  shall  have  been  obliterated  by 
Je  caving  of  the  banks.  This  combined  party,  traversing  short  lines, 
pleasuring  elevations,  and  sounding  out  cross-sections,  has  advanced 
*0  miles  and  made  connection  with  the  work  of  examination  party  in 
e  vicinity  of  Plum  Point.  It  is  anticipated  that  it  will  carry  its  work 
Memphis  during  the  present  season;  beyond  this,  for  a  distance  of 
j)  miles,  complete  maps  exist  from  the  survey  made  by  General  Comstock 
ffore  the  Commission  was  created. 

At  the  time  the  Commission  was  organized  charts  had  been  published 
the  Coast  and  Geodetic  Survey  of  the  portion  of  the  river  lying  be- 
peen  Point  Houma  (about  72  miles  above  ^few  Orleans  and  the  Gulf), 
lowing  depths  of  water,  with  marginal  topography;  so  that  there  re- 
ained  for  this  Commission  to  execute,  in  the  river  .below  Cairo,  about 
)0  miles  of  surveys  of  the  skeleton  form  above  indicated. 

Precise  levels. — Prom  employes  of  the  Commission  two  parties  were 
^signed  to  run  a  line  of  precise  levels,  in  duplicate,  and  in  opposite 
irections,  with  permanent  bench-marks  every  three  miles,  so  located 
ad  marked  that  they  may  be  relied  upon  for  at  least  twenty  years, 
he  most  accurate  instruments  known  to  engineers  were  placed  in  the 
ands  of  these  parties,  and  they  were  instructed  that  the  discrepancy  in 
uplicate  lines  of  levels  should  not  exceed  omm,  x  the  square  root  of 
le  distance  in  kilometers. 

They  began  their  work  at  Columbus,  20  miles  below  Cairo,  at  tho 
nomination  of  a  series  of  levels  previously  executed  by  General  Com- 
tock,  and  have  advanced  to  Cottonwood  Point,  120  miles  below  Cairo, 
'hey  will  probably  reach  Memphis  by  the  middle  of  April,  should  no  in¬ 
terruption  from  Hoods  occur.  Here  they  will  connect  again  with  a  series 
f  levels  executed  by  General  Comstock  which  extends  about  83  miles 
jelow. 

It  is  proposed  to  put  another  leveling  party  into  the  field  as  soon  as 
roper  instruments  are  obtained,  and  if  this  additional  party  can  pursue 
ts  work  until  the  first  of  May  the  precise  levels  will  be  brought  nearly 
jo  the  mouth  of  White  Elver,  where  the  triangulation  of  this  season 
rill  probably  terminate,  as  above  stated. 

In  the  lower  portion  of  the  river  two  parties  of  the  Coast  and  Geodetic 
Survey  are  running  similar  lines  of  precise  levels  between  Carrollton 
ind  Greenville,  and  the  superintendent  expects  to  be  able  to  keep  this 
Vork  in  progress  during  the  entire  season  and  close  this  space  of  500 
miles  by  the  end  of  the  fiscal  year. 

\  Examinations. — Three  localities  have  been  selected  at  which  surveys 
are  repeated  frequently  to  ascertain  the  varyiug  relations  of  the  river 
and  its  bed  ;  these  are  Plum  Point  and  its  approaches,  Lake  Providence 
and  its  neighborhood,  and  Carrollton  ;  the  last  named  being  selected 


6 


REPORT  OF  MISSISSIPPI  RIVER  COMMISSION. 


because  it  was  the  site  of  similar  inquiries  during  the  surveys  of  Ilnlim 
phreys  and  Abbot  in  1858. 

The  observations  at  these  places  comprise  tlie  changes  in  the  figi  |ire 
of  the  river  bed  at  different  stages  of  the  water,  the  kind  of  matei 
forming  or  moving  along  the  bed,  the  figure  and  movements  of  sac  »d- 
waves,  the  slope  of  water  surface,  the  discharge,  and  the  transve:  f s0 
curves  of  velocity. 

The  parties  engaged  in  these  physical  surveys  are  employes  of  il'hc 
Commission,  many  of  whom  had  previously  been  engaged  in  simijlhir 
studies.  They  commenced  work'  in  the  low  river  season,  and  it  is  hopl|e(i 
that  the  funds  available  will  enable  them  to  continue  till  the  spring 
floods  have  subsided. 

Borings. — A  boring  party  has  been  organized  to  determine  the  dep 
of  the  alluvial  deposits  and  the  character  of  underlying  strata  in  por¬ 
tions  of  the  river  requiring  improvement.  These  borings  have  be|P11 
finished  in  the  vicinity  of  Memphis  and  Helena,  and  others  are  to  B-”3 
made  at  Choctaw  Bend  and  other  points. 


th 


SURVEYS  AND  EXPENSES  OF  COMMISSION. 

It  is  necessary  that  the  surveys  and  examinations  which  have  be^T0 
undertaken  by  the  Commission  and  are  now  in  progress  below  Caii.vh 
under  the  authority  conferred  in  section  3  of  the  act,  should  be  continued^* 
and  that  surveys  should  be  commenced  above  Cairo,  so  far  as  they  m? 
be  considered  necessary  for  the  advantageous  progress  of  works  of  id 
provement.  For  these  purposes  and  for  salaries,  mileage,  traveling  ad  1 
office  expenses  of  the  Commission,  there  will  be  required  during  tl[je 
coming  fiscal  year  the  sum  of  $200,000. 

In  view  of  the  prospect  of  an  extreme  flood  on  the  Lower  Mississipf 
which  would  afford  an  unusual  opportunity  for  observations  upon  tlue 
operations  of  floods,  the  importance  of  an  early  appropriation  of  tl  ie 
amount  estimated  for  surveys  under  the  Commission  is  earnestly  repre¬ 
sented,  in  order  that  the  system  of  observations  already  inaugurate 
may  be  made  continuous  through  the  flood  season. 


SYSTEMS  OF  IMPROVEMENT. 


e 

Pil 


This  Commission  is  not  prepared,  nor  is  it  deemed  necessary  at  th 
present  time,  to  submit  a  full  and  detailed  report,  with  estimates  of  fim 
cost,  upon  any  general  system  of  river  improvement.  It  seems  prope  L 
however,  that  all  the  several  methods  and  plans  embraced  by  the  com¬ 
prehensive  and  distinctive  language  used  in  the  act,  so  far  as  they  appl.y 
to  or  have  direct  bearing  upon  any  of  the  objects  contemplated  thereif1? 
should  be  defined,  and  that  the  general  principles  which  have  been  kepyk 
in  view  in  adopting  a  plan  which  will  concentrate  rather  than  dispersj0 
the  waters  of  the  river,  as  the  principal  agent  in  securing  the  needed 
improvement  in  its  navigation,  should  be  briefly  stated. 

Whatever  seems  needful  to  be]said  upon  the  “  outlet  system,”  which  i 
being  one  of  diffusion  and  waste  and  not  of  concentration,  does  nc'f 
commend  itself  to  the  judgment  ot  the  Commission,  will  be  embodied  ii-1 
this  report. 

The  Mississippi  Liver,  aside  from  its  great  length  and  other  elementSj 
of  wonderful  and  impressive  magnitude,  and  the  energy  with  which  it^ 
maintains  its  tortuous  and  everchanging  route  to  the  sea,  ranging  over' 
a  broad  alluvial  region  of  its  own  creation,  does  not  appear  to  be  char 
acterized  by  any  phenomena  peculiar  to  itself,  or  by  any  physical  fea- 


) 


REPORT  OF  MISSISSIPPI  RIVER  COMMISSION. 


7 


tures  not  found  in  greater  or  less  degree  in  other  turbid  streams  flowing 
through  alluvial  deposits.  Its  waters  within  the  limits  of  the  alluvial 
district  constantly  carry  large,  although  very  variable,  quantities  of  sed¬ 
imentary  matter.  This  sediment,  or  silt,  derived  from  tributary  streams, 
from  caving  banks,  and  from  its  own  bed  by  erosion  and  scour,  is  borne 
along  by  the  current  in  such  manner  that  a  large  part  of  it  is  held  in 
more  or  less  constant  suspension  in  the  water,  while  a  portion  is  rolled 
or  swept  along  upon  the  bottom. 

An  exact  relation  between  the  quantity  of  silt  transported  or  moved 
along  by  a  stream,  and  the  longitudinal  velocity  of  its  current,  has  not 
been  discovered.  Longitudinal  velocity,  however,  is  always  accom¬ 
panied  by  motion  in  other  directions.  Without  upward  motiou  of  the 
water,  there  can  be  no  continued  suspension  of  sedimentary  matter 
in  it. 

When,  on  any  given  reach  of  the  same  stream,  the  velocity,  as  usually 
measured  by  meters  or  floats,  is  increased,  the  vertical  motion,  and  there¬ 
fore  the  silt  sustaining  and  transporting  power  of  the  stream,  is  also 
increased.  It  does  not  follow  from  this,  however,  that  in  different  silt¬ 
bearing  streams,  or  in  different  reaches  of  the  same  stream,  or  even  in 
the  same  reach  through  varying  stages  of  water  or  different  seasons  of 
the  year,  the  same  velocity  of  current  invariably  sustains  and  transports 
the  same  amount  or  proportion  of  sedimentary  matter.  No  fixed  rela¬ 
tion  has  been  discovered  between  a  volume  of  water  and  the  amount  of 
sediment  iu  it  for  any  given  observed  velocity.  The  supply  of  earthy 
matter  is  very  irregular,  varying  greatly,  irrespective  of  changes  of  ve¬ 
locity,  with  fluctuations  in  the  stage  of  river,  the  relative  discharge  of 
different  tributaries,  the  seasons  of  the  year,  the  conditions  governing 
rainfall,  alternations  of  freezing  aud  thawing,  the  kind  of  crops  cultivated 
in  the  vicinity,  aud  other  causes. 

Any  reduction  of  velocity  by  lessening  the  sustaining  and  transport¬ 
ing  power  of  the  water,  and  by  arresting  some  of  the  heavier  particles 
which  the  diminished  current  is  unable  to  move  along  upon  the  bottom, 
will  tend  to  cause  a  deposit  of  solid  earthy  matter  and  raise  the  bed  of 
the  stream.  The  direct  effect  of  raising  the  bed  is  to  raise  the  surface 
slope.  The  surface  slope  may  also  be  increased  by  reduction  of  the 
river’s  length  by  cut  offs  and  other  causes. 

Conversely,  if  the  velocity  be  increased  from  any  cause,  a  greater 
amount  of  silt  will  be  thrown  into  suspension,  which  will  be  supplied  by 
erosion.  A  lowering  of  both  the  bed  of  the  stream  and  the  surface  slope 
will  therefore  ensue. 

These  general  principles  may  be  briefly  aud  comprehensively  stated 
as  follows,  viz:  If  the  normal  volume  of  water  in  a  silt-bearing  stream 
flowing  iu  an  alluvial  bed  of  its  own  formation  be  permanently  in¬ 
creased,  there  will  result  an  increase  of  velocity,  and  consequently  of 
erosion  and  silt-beariug  power,  an  increase  in  area  of  average  cross-sec¬ 
tion,  aud  an  ultimate  lowering  of  the  surface  slope  ;  and,  conversely,  if 
the  normal  flow  be  decreased  in  volume,  there  will  erjsue  a  decrease  of 
velocity,  silt-transporting  power,  and  mean  sectional  area,  and  an  ulti¬ 
mate  raising  of  the  surface,  slope. 

THE  OUTLET  SYSTEM. 

It  has  been  supposed  bynnany  persons  that,-  because  the  immediate 
effect  of  a  crevasse  during  a  flood  is  the  reduction  of  the  height  of  the 
river’s  surface  in  the  vicinity  of  the  crevasse  and  below  it,  lateral  outlets, 
either  natural  or  artificial,  by  which  the  flood- waters  of  the  river  are 


8 


REPORT  OF  MISSISSIPPI  RIVER  COMMISSION. 


drawn  oft'  and  conveyed  through  a  shorter  route  to  the  sea,  tend  to  pre¬ 
vent  the  recurrence  of  destructive  floods,  by  supplying  additional  ave-  < 
nues  for  their  escape.  This  method  would  undoubtedly  be  effective  if 
the  flood-waters  of  the  Mississippi  were  not  highly  charged  with  sedi¬ 
mentary  matters,  which  are  held  in  suspension  in  the  water  by  the  cur¬ 
rent.  To  support  this  immense  mass  of  earth  and  sand  in  suspension,  t 
and  thus  insure  its  transportation  to  the  Gulf,  the  velocity  of  the  current 
must  be  sustained.  Without  stopping  to  determine,  or  even  discuss, 
the  character  of  the  relation  which  exists  between  the  various  velocities 
of  current  and  the  proportionate  quantities  of  sediment  which  such  ve¬ 
locities  are  capable  of  carrying  in  suspension,  the  fact  seems  to  be  estab¬ 
lished  that  when  the  current  is  checked  in  its  natural  flow  during  floods, 
a  deposit  of  sediment  will  occur.  Shoals  are  found  in  the  river  immedi¬ 
ately  below  crevasses,  which  it  is  difficult  to  refer  to  any  other  cause  than 
the  loss  of  current- velocity  which  takes  place  below  the  crevasse.  As  a 
portion  of  the  volume  of  the  river  is  drawn  off  by  the  crevasse  when  it 
is  first  made,  it  is  impossible  that  the  current  below  the  crevasse  can 
then  be  as  rapid  as  it  was  before  its  occurrence.  Being  less  rapid,  it  is 
unable  to  sustain  the  whole  quantity  of  matter  held  in  suspension  by 
the  more  rapid  current  above  the  outlet,  and  consequently  its  surplus 
sediment  falls  to  the  bottom  below  the  crevasse.  This  deposition  con¬ 
tinues  until  the  size  of  the  river  below  the  crevasse  has  been  so  reduced 
by  the  shoaling  that  the  current  is  again  restored  through  the  short 
distance  in  which  the  bottom  of  the  river  has  been  thus  raised  and  the 
channel  diminished.  If  the  crevasse  remained  open,  however,  for  sev¬ 
eral  years,  it  is  evident  that  the  shoal  will  continue  to  extend  down  the 
stream,  for  the  reduced  velocity  will  still  exist  in  the  river  below  the 
shoal.  If  the  crevasse  be  kept  open  indefinitely,  the  shoaling  will  con¬ 
tinue  to  extend  down  the  stream  until  certain  other  injurious  effects  are 
produced,  which  will  be  presently  referred  to. 

It  is  a  well  established  law  of  hydraulics  that  the  ratio  of  frictional 
resistance  per  unit  of  volume  increases  if  the  sectional  area  be  dimin¬ 
ished.  Thus,  if  the  volume  of  the  river  were  suddenly  divided  by  an 
island  into  two  channels,  the  water  flowing  in  them  would  encounter 
more  frictional  resistance  than  it  met  with  while  flowing  in  a  single 
channel.  Hence  the  currents  through  these  channels  would  be  more 
sluggish.  As  the  water  is  charged  with  sediment  the  sluggish  current 
would  cause  a  deposit  in  the  channels  which  would  first  begin  at  their 
upper  ends,  and  would  continue  until  the  bottoms  of  the  two  channels 
would  be  so  steepened  that  the  current  would  attain  a  velocity  capable 
of  carrying  the  suspended  sediment  through  them  without  further 
deposit.  If  the  two  channels  were  of  nearly  equal  length  and  size,  they 
would  probably  remain  permanent,  and  the  slope  of  the  river’s  surface 
in  flood  time  would  be  found  to  be  steeper  through  them  than  above  and 
below,  where  the  volume  flows  in  a  single  channel.  If  one  of  the  two 
channels  were  materially  longer  than  the  other,  the  effort  of  the  river 
to  increase  the  steepness  of  the  longer  channel  would  be  abortive,  be¬ 
cause  its  slope  would  be  controlled  by  the  shorter  one.  A  shoal  in  the 
upper  end  of  the  long  channel  would,  however,  be  built  up  to  such 
height  by  the  depositing  action  of  the  sluggish  water  in  it,  as  finally  to 
shut  it  off  altogether  from  any  connection  with  the  river,  while  the  still 
water  at  the  lower  end  of  such  chaunel  would  promote  the  deposition  of 
sediment  at  that  end  to  such  an  extent  as  to  build  it  up  also,  and  thus  ^ 
completely  separate  the  long  channel  from  the  main  body  of  the  river; 
in  the  mean  time  the  shorter  channel  would  have  enlarged  so  as  to  ac¬ 
commodate  the  entire  river.  The  longer  channel  would,  in  this  event, 


REPORT  OF  MISSISSIPPI  RIVER  COMMISSION. 


9 


constitute  a  lake,  like  one  of  tlie  many  lakes  which  are  seen  on  a  map  of 
the  alluvial  basin  of  the  river.  Being  removed  from  the  influence  of 
overflows,  these  lakes  remain  deep  and  clear  for  many  centuries.  The 
phenomenon  just  described  invariably  accompanies  the  formation  of  a 
cut-off.  When  one  of  these  occurs,  the  volume  of  the  river  is  at  first 
divided  into  two  channels  of  unequal  length,  an  island  being  left  be¬ 
tween  them. 

In  the  case  of  a  crevasse  an  island  is  also  formed,  having  the  main 
body  of  the  river  on  the  one  side  of  it,  and  the  crevasse  channel  on  the 
other  side.  As  the  volume  flowing  in  the  main  channel  below  a  crevasse 
lias  been  decreased  by  the  amount  drawn  off  through  it,  a  steeper  slope 
in  the  main  river,  if  the  crevasse  be  kept  permanently  open,  becomes 
inevitable;  because  the  shoal  below  the  outlet,  as  it  grows  in  leugth 
down  stream  from  the  deposition  of  successive  floods,  gradually  increases 
the  frictional  resistance  of  the  volume  flowing  through  that  diminished 
channel,  and  this  tends  to  check  the  current  of  the  river  above  the 
crevasse,  and  thus  the  shoaling  of  the  river  bed  and  the  raising  of  the 
flood  line  above  the  site  of  the  outlet  ensue  as  a  secondary  and  permanent 
effect. 

It  is  in  this  way  that  silt-bearing  streams  flowing  through  alluvial  de¬ 
posits  have  the  ability  to  increase  or  steepen  their  surface  slopes,  and 
thus  recover  the  velocity  of  their  currents  and  adjust  them  to  the  work 
of  transporting  the  sedimentary  matter  with  which  the  flood- waters  are 
charged  so  that  this  matter  may  be  carried  without  loss  or  gain.  In 
proof  of  the  correctness  of  these  views,  and  of  their  full  accordance  with 
well  established  hydraulic  laws,  we  have  the  evidence  of  this  relation 
between  slope  and  volume  presented  in  the  phenomena  of  silt-bearing 
streams  all  over  the  world.  Wherever  such  streams  flow  through 
alluvial  deposits,  other  conditions  being  the  same,  the  slope  is  least 
where  the  volume  is  greatest ;  and,  conversely,  the  slope  is  found  to  be 
invariably  increased  as  the  volume  is  diminished.  The  Mississippi 
throughout  its  alluvial  basin,  not  only  in  its  main  trunk  but  in  all  of  its 
outlets,  presents  no  exception  to  this  peculiar  feature.  Among  numer¬ 
ous  illustrations  of  this  law  the  following  examples  may  be  cited. 

The  fall  of  the  Atchafalaya  is  about  six  inches  per  mile  from  its  head 
to  the  Gult  level,  while  the  fall  of  the  Mississippi  from  the  same  point 
is  less  than  two  inches  per  mile.  The  volume  of  the  Atchafalaya  is  only 
about  one-twelfth  as  great  as  that  of  the  Mississippi  where  they  sepa¬ 
rate.  The  fall  of  the  South  Pass  is  three  inches  per  mile,  whilst  that  of 
the  Southwest  Pass  is  but  two  inches  per  mile.  The  volume  of  the  South 
Pass  is  only  about  one  quarter  as  large  as  that  of  the  Southwest  Pass. 

As  water  selects  the  line  of  least  resistance  in  flowing  from  a  higher 
to  a  lower  level,  it  folloAVS  that,  inasmuch  as  that  portion  of  the 
Mississippi  floods  which  enters  the  A  tchafalaya  seeks  the  Gulf  level 
through  a  route  not  half  so  long  as  that  which  follows  the  main  river, 
and  as  it  has  a  descent  threefold  greater  than  the  portion  that  flows 
in  the  main  liver,  the  resistance  in  the  shorter  and  steeper  route  of 
the  Atchafalaya  must  be  so  much  greater  that  these  elements  which 
tend  to  increase  the  current  are  so  far  neutralized  as  to  produce  in  both 
routes  to  the  sea  that  rate  of  current  which  is  capable  of  transporting 
the  sediment  without  loss  or  gain  to  the  Gulf  level,  and  thus  a  condition 
of  equilibrium  is  established  between  these  two  routes  to  the  sea.  It 
seems  unnecessary  to  state  that  the  ratio  of  frictional  resistance  to  vol¬ 
ume  of  water  resulting  from  the  smaller  size  of  the  Atchafalaya  is  so 
much  greater  than  that  in  the  main  river,  that  this  condition  of 
equilibrium  or  regimen  of  the  two  channels  is  the  result.  Anything 


10 


REPORT  OF  MISSISSIPPI  RIVER  COMMISSION. 


which  will  tend  to  increase  the  flow  permanently  through  either  route 
would,  if  unchecked,  have  a  tendency  to  cause  the  entire  river  to  find 
its  way  ultimately  through  that  route  to  the  sea  by  lessening  in  it,  as  it 
enlarged,  the  ratio  of  frictional  resistance  to  volume  of  water  Rowing  in 
if.  The  subdelta  building  ability  of  the  smaller  passes  by  which  they 
prolong  their  length  and  thus  flatten  their  slopes,  will  invariably  tend 
to  cause  their  extinction  by  results  similar  to  those  hereinafter  referred 
to  at  Cubitt’s  Gap,  the  Jump,  and  the  extinct  outlets  below  them.  This 
cause  has  tended  to  the  extinction  of  many  well  known  bayous  below  the 
Atchafalaya.  That  the  Atchafalaya  remained  so  long  unaltered,  and  is 
now  evidently  enlarging,  is  owing  to  important  changes  in  the  bed  of 
the  Mississippi  near  it,  by  which  a  large  portion  of  the  floods  of  Red 
River  have  been  recently  discharged  through  it. 

This  explanation  of  the  relation  between  slope  and  volume  is,  of  . 
course,  applicable  to  the  other  existing  outlets  referred  to  in  this  con¬ 
nection.  For  this  reason  the  Commission  believes  that  no  surer  method 
of  ultimately  raising  the  flood-surface  of  the  river  can  be  adopted  than 
by  making  lateral  outlets  for  the  escape  of  its  flood-waters.  The  rais¬ 
ing  of  the  flood-surface  necessitates  an  increase  in  the  height  of  the 
levees  and  leaves  shallower  channels  for  navigation. 

As  the  system  of  improvement  proposed  by  the  Commission  is  based 
upon  a  conservation  of  the  flood-waters  of  the  river,  and  their  concen¬ 
tration  into  one  channel  of  an  approximately  uniform  width,  it  would 
seem  scarcely  necessary  further  to  consider  a  system  based  upon  theo¬ 
ries  and  arguments  so  diametrically  opposed  to  it  as  the  outlet  system 
is  thus  shown  to  be. 

Allusion  has  only  been  made  so  far  to  phenomena  attending  long 
established  or  permanent  outlets.  A  proposition  to  provide  for  im¬ 
proving  the  navigation  of  the  Mississippi  River  and  for  the  reclama¬ 
tion  of  the  low  lauds  of  the  States  bordering  thereon”  having  been  pre¬ 
sented  to  the  consideration  of  Congress  in  House  bill  5113,  Forty-fifth 
Congress,  third  session,  it  is  the  duty  of  the  Commission  to  report  upon 
the  merits  of  the  system  as  set  forth  in  the  bill.  The  first  feature  of 
the  plan  consists  in  opening  an  outlet,  about  ten  miles  below  New  Or¬ 
leans,  from  the  river  into  Lake.Borgne.  The  idea  of  making  an  outlet 
into  this  lake  was  suggested  by  Mr.  Charles  Ellet,  j r.,  civil  engineer,  in 
1852  (see  Ex.  Doc.  20,  Thirty-second  Congress,  first  session),  in  an 
elaborate  report  to  the  Secretary  of  War  on  the  inundation  of  the  Mis¬ 
sissippi  River. 

The  proposition  was  subsequently  discussed  at  considerable  length 
in  the  report  of  Humphreys  and  Abbot,  and  rejected  by  them  as  im¬ 
practicable.  It  was  again  taken  up  and  examined  into  by  the  Levee 
Commission  in  1875,  and  was  by  it  likewise  rejected. 

In  considering  the  proposed  outlet  at  L  ike  13  )rgne,  it  is  necessary  to 
refer  to  phenomena  attending  a  class  of  outlets  which  cannot  be  con¬ 
sidered  as  permanent  ones,  and  which  are  similar  in  their  characteristics 
to  those  which  would  attend  the  proposed  one  at  Lake  Borgne,  for  the 
reason  that  the  river  immediately  after  their  occurrence,  whether  from 
artifical  or  natural  causes,  commences  a  process  of  subdelta  formation 
which  in  the  course  of  a  few  years  effects  their  complete  closure. 

On  examination  of  the  appended  United  States  Coast-Survey  map, 
showing  that  part  of  the  delta  embracing  the  passes  and  about  forty 
miles  from  the  main  river,  several  remarkable  systems  of  extiuct  chan¬ 
nels  will  be  found  on  each  side  of  the  three  great  passes.  The  vermicu- 
lated  appearance  of  these  old  outlets  is  particularly  noticable  on  the 
west  side  of  the  Southeast  Pass  and  on  the  west  side  of  the  Southwest 


REPORT  OF  MISSISSIPPI  RIVER  COMMISSION. 


11 


Pass.  The  process  by  which  the  river  closed  them  up  and  shut  them 
*  off  is  clearly  illustrated  by  a  similar  process  uow  occurring  about  three 
miles  above  the  Head  of  the  Passes.  At  this  point  on  the  map  referred 
to  will  be  seen  the  largest  and  most  recent  outlet  or  mouth  of  the  Mis¬ 
sissippi.  It  occurred  during  a  flood  seventeen  years  ago,  and  is  known 
^  as  Cubitffs  Gap.  It  was  caused  by  a  small  canal  between  the  river  and 
the  Gulf,  used  by  fishermen  in  visiting  the  oyster  banks  in  the  vicinity. 

The  river  and  the  Gulf  at  this  point  were  then  separated  by  a  narrow 
margin  less  than  one  thousand  feet  wide.  The  difference  in  the  surface 
height  of  the  river  and  the  mean  level  of  the  Gulf  at  the  time  was  a 
little  over  three  feet.  The  surface  slope  or  fall  through  the  gap  was 
therefore  at  first  at  the  rate  of  about  fifteen  feet  per  mile.  The  rapidity 
of  the  escaping  water  with  this  enormous  fall  made  the  crevasse  over 
two  thousand  feet  wide  in  a  few  years,  with  depths  of  one  hundred  feet 
and  over  in  the  gap  where  the  river  bank  had  formerly  stood. 

As  soon  as  the  water  passed  through  the  gap  its  velocity  was  gradu¬ 
ally  lost,  and  the  immense  volume  of  sediment  with  which  it  was  charged 
was  thrown  down  within  a  fan-shaped  area  embracing  probably  twenty 
or  thirty  square  miles.  The  earlier  maps  of  the  Coast  Survey  show  no 
islands  outside  the  gap,  but  the  more  recent  ones  show,  by  the  incipient 
islands  and  shoals  which  now  surround  it,  how  rapid  has  been  its  sub¬ 
delta  formation.  These  islands  are  subdividing  the  single  volume  of 
the  river  water  issuing  from  it  into  innumerable  bayous  and  little  chan¬ 
nels,  none  of  them  having  at  this  time  a  greater  depth  than  7  feet. 
Each  flood  serves  to  build  up  these  islands  higher  and  extend  their  area 
further  into  the  Gulf.  And  as  this  island-building  process  continues 
out  gulfward,  these  small  channels  become  more  distinctly  outlined  from 
j  the  depositing  action  which  goes  on  most  rapidly  in  the  more  sluggish 
water  along  their  shore  lines.  Every  overflow  serves  to  build  up  the 
banks  of  these  channels  and  to  extend  them  out  into  the  gulf,  but  in 
their  prolongation  is  to  be  found  the  cause  which  finally  cuts  off  and 
'  separates  them,  perhaps  forever,  from  the  main  river.  The  difference 
of  level  between  the  river  and  the  Gulf  remains  the  same  that  it  was  at 
the  time  of  the  crevasse,  but  the  enormous  slope,  through  the  gap,  at 
first  equal  to  about  15  feet  per  mile,  and  which  must  have  created  an 
exceedingly  rapid  current  during  the  first  few  days  after  the  gap  was 
made,  now  no  longer  exists.  Every  addition  to  the  length  of  the  sep¬ 
arate  channels  which  are  now  forming  through  the  subdelta  flattens 
their  slope  and  consequently  reduces  the  current  through  them.  Ulti¬ 
mately  these  currents  will  become  too  sluggish  to  transport  the  sediment 
contained  in  the  water,  and  it  will  be  dropped  at  the  upper  or  river  ends 
of  these  channels,  and  they  will  be  finally  shut  off  entirely  from  all  con¬ 
nection  with  the  main  river,  just  as  those  were  which  are  seen  on  the  map 
on  the  west  side  of  Southwest  and  Southeast  passes. 

Each  successive  overflow  of  the  river  bank  will  tend  to  increase  the 
distance  between  the  river  and  these  extinct  outlets,  and  the  wound 
made  in  the  side  of  the  river  by  Oubitt’s  Crevasse  wiil  then  have  been 
completely  healed  by  a  natural  process. 

Twenty-one  miles  above  the  Head  of  the  Passes,  a  gap  similar  to  Cu- 
bitt’s  occurred  about  forty  years  ago,  called  “  The  Jump.”  Au  immense 
subdelta  was  formed  there  in  consequence,  and  upon  it  there  are  now 
several  rice  plantations  and  extensive  forests,  many  of  the  trees  being 
r;  over  12  inches  in  diameter. 

Innumerable  bayous  permeate  this  subdelta  and  lead  to  the  sea, 
each  having  at  its  mouth  a  miniature  bar  like  those  at  the  mouths  of 


12 


REPORT  OF  MISSISSIPPI  RIVER  COMMISSION. 


the  great  passes,  none  of  them  having  more  than  2  feet  of  depth  at  low- 
water. 

At  the  river  entrance  to  the  The  Jump,  the  depth  is  but  -3  or  4  feet, 
and  in  a  few  years  more  it  will  be  fully  closed  by  the  river  deposits. 

The  same  effort  which  the  river  is  successfully  making  to  close  np 
The  Jump  and  Cubitt’s  Crevasse  (both  of  which  are  high  and  low  water 
outlets),  it  is  making  at  the  celebrated  Bonnet  Carre  Crevasse,  which, 
being  through  an  artificial  embankment  or  levee,  only  discharges  at 
high-water.  The  immense  deposits  which  it  has  carried  out  and  spread 
over  the  land  near  it  have  served  greatly  to  reduce  the  volume  of  water 
discharged  by  the  crevasse. 

Should  an  outlet  be  made  to  connect  the  river  with  Lake  Borgne,  re¬ 
sults  precisely  similar  to  those  which  have  occurred  at  Cubitt’s  Gap  and 
The  Jump  must  be  confidently  anticipated.  Below  Cubitt’s  Gap  it  is  an 
undisputed  fact  that  the  former  depth  of  the  river  has  been  largely  re¬ 
duced  since  the  gap  occurred.  Below  The  Jump  it  is  not  so  definitely 
known  what  the  shoaling  has  been,  as  charts  of  previous  soundings  are 
not  now  available  if  any  exist,  but  the  Light-House  Board  has  placed 
two  buoys  a  short  distance  below  The  Jump,  to  warn  vessels  away  from 
the  shoals  which  exist  there.  It  is  not  possible  to  make  the  proposed 
outlet  into  Lake  Borgne  without  creating  a  shoal  in  the  river  below  it, 
and  it  is  not  possible  to  keep  it  permanently  open  except  at  great  cost 
in  dredging  away  the  subdelta  that  would  be  formed  by  it.  Nor  could 
it  be  kept  permanently  open  without  the  slope  of  the  river  being  ulti¬ 
mately  increased  from  the  Head  of  the  Passes  to  the  outlet ;  after  which 
it  would  raise  the  Hood  surface  of  the  river  above  the  outlet. 

With  reference  to  that  part  of  the  plan  set  forth  in  House  bill  5413, 
relating  ro  the  Atchafalaya  outlet,  the  Commission  suggest  that,  as 
Major  Benyaurd,  of  the  United  States  Corps  of  Engineers,  in  charge  of 
the  government  works  upon  this  portion  of  the  Mississippi,  has  now 
under  consideration  the  question  of  the  permanent  improvement  of  the 
mouth  of  the  Bed  Biver,  with  the  intention,  as  expressed  in  his  last 
annual  report,  of  making  a  special  report  thereon  at  the  earliest  possible 
moment,  it  is  not  deemed  advisible  that  any  work  at  this  locality,  except 
what  may  be  required  to  check  the  enlargement  of  the  Atchafalaya, 
should  be  recommended  by  this  Commission  in  anticipation  of  the  ma¬ 
tured  views  and  opinions  of  that  officer.  This  can  be  done  in  such 
locality  and  in  such  manner  as  will  not  interfere  with  the  navigation  of 
the  Bed  and  Atchafalaya  Bi vers,  and  at  a  cost  not  exceeding  $10,000. 

That  part  of  the  plan  which  involves  turning  the  Bed  Biver  into  the 
Calcasieu,  from  a  point  above  Alexandria,  is  entirely  impracticable,  it 
having  beeu  ascertained  by  a  line  of  levels  run  across  from  Alexandria, 
under  Major  Benya urd’s  direction,  that  the  bed  of  the  Calcasieu  Biver 
is  G3  feet  higher  than  the  water  surface  of  Bed  Biver  in  time  of  ordi¬ 
nary  flood,  while  its  ordinary  flood  level  is  73  feet  above  that  of  Bed 
Biver.  The  distance  between  the  two  rivers,  on  the  line  of  levels,  which 
is  the  shortest  line  that  can  be  run  from  Alexandria,  is  23.8G  miles. 

If  it  is  proposed  to  avoid  this  difficulty  by  making  the  connection  with 
the  Calcasieu  at  a  point  sufficiently  near  its  mouth  to  secure  the  requisite 
descent  in  the  cut,  not  only  would  the  expense  be  so  enormous  as  to  be 
practically  prohibitory,  but  there  would  still  remain  the  danger,  unless 
the  dimensions  of  both  the  cut  and  the  lower  Calcasieu  be  made  im¬ 
moderately  large,  of  widespread  destruction  by  floods  during  every  high- 
liver  stage  through  the  region  traversed  by  the  outlet. 

Although  other  equally  novel  propositions  are  setforth  for  considera¬ 
tion  by  Congress  in  House  bill  No.  5113,  as  part  of  this  extensive  outlet 


REPORT  OF  MISSISSIPPI  RIVER  COMMISSION. 


13 


system,  which  in  the  language  of  the  bill  is  designed  to  effect  the  u  deep¬ 
ening  of  the  channel  of  the  Mississippi  River,  reducing  the  mud  flow 
■\  therein,  and  filling  up  the  swamps  and  low  places  by  the  deposit,  and 
diminishing  the  volume  of  water  by  absorption  and  evaporation,”  the 
Commission  deems  it  unnecessary  to  report  upon  them  in  detail  after  this 
exposition  of  the  Lake  Borgne  and  Calcasieu  outlets,  inasmuch  as  the 
latter  constitute  the  chief  features  of  the  entire  scheme,  and  the  former 
are,  like  them,  quite  impracticable. 

Before  dismissing  this  subject,  however,  it  is  pertinent  to  say  that  the 
statements  which  have  been  published  to  support  this  scheme,  regarding 
the  effect  produced  by  the  Bonnet  Carre  outlet,  in  lowering  the  flood-line 
above  and  below  it,  have  been  greatly  exaggerated. 

The  Board  of  Engineers  for  the  improvement  of  the  low-water  navi¬ 
gation  of  the  Mississippi  River  below  Cairo,  to  whom  House  bill  No. 
5413  was  referred,  say  in  their  report  of  January  28,  1879,  with  reference 
to  the  effect  of  the  proposed  outlet : 

The  probable  immediate  effect  of  this  outlet  upon  the  Hood-level  of  the  Mississippi 
will  next  be  considered.  The  best  basis  for  a  safe  estimate  is  the  measured  effect  of 
the  Great  Bell  crevasse  which  occurred  just  above  New  Orleans  on  the  right  bank,  in 
1858.  Its  maximum  discharge  occurred  August  1-17,  and  was  80,000  cubic  feet  per 
second,  or  about  1-12  of  the  total  discharge  of  the  river  at  that  date. 

This  lowered  the  water  surface  1.5  feet  at  its  site  and  produced  no  sensible  effect  at 
Baton  Rouge,  124  miles  above.  One  fundamental  error  of  the  engineering  project  on 
which  this  bill  is  based  lies  in  overestimating  the  distance  to  which  the  inlluence  of 
an  outlet  extends  above  its  site,  and  it  will  be  well  to  elaborate  this  point. 

The  influence  of  the  Gulf  upon  the  river  at  high  stages  is  hardly  felt  above  the  mouth 
of  Reel  River.  The  high-water  and  the  low- water  slopes  of  the  water  surface  above 
this  point  are  sensibly  the  same  for  long  distances.  Nothing  can  be  done  toward  mod¬ 
ifying  the  water-level  below  which  will  exert  any  marked  effect  at  any  considerable 
distance  above.  That  this  is  so  was  proved  by  the  Red  River  and  Raccourci  Cut-offs, 
*  which  shortened  the  Mississippi  39  miles  near  the  mouth  of  Red  River  and  lowered  the 
high-water  mark  there  4.6  feet  in  the  flood  of  1851.  This  beneficial  effect  diminished 
rapidly  at  points  higher  up  the  river,  and  was  not  felt  at  all  at  a  distance  of  100 
miles. 

The  same  principle  of  hydraulics  which  is  fundamental,  and  which  logically  results 
✓  from  the  small  function  of  the  slope  entering  all  discharge  formulae,  is  also  illustrated 
by  accurate  tidal  measurements  upon  the  Mississippi.  Thus,  for  spring  tides  the  oscil¬ 
lations  are — 

At  the  Gulf  in  flood  stages  of  river,  1.7  feet;  in  low  stages  of  river,  1.7  feet. 

At  the  Forts  (36  miles)  in  flood  stages  of  the  river,  0.6  foot;  in  low  stages  of  river, 
1.4  feet. 

At  Carrollton  (120  miles)  in  flood  stages  of  the  river,  0.3  foot;  in  low  stages  of  river, 

1.1  feet. 

At  Donaldsouville  (192  miles)  in  flood  stages  of  the  river,  0.0  ;  but  in  low  stages  of 
river,  0.9  foot. 

At  Baton  Rouge  (244  miles)  in  flood  stages  of  the  river,  0.0  foot ;  in  low  stages  of 
river,  0.4  foot. 

At  Red  River  (315  miles)  in  flood  stages  of  the  river,  0.0  foot;  in  low  stages  of  river, 
0.0  foot. 

It  is  true  that  the  temporary  duration  of  the  tidal  rise  at  the  river  mouth  diminishes 
its  effect  on  the  upper  river,  but  nevertheless  the  facts  given  for  the  tides  illustrate 
the  general  fact  that  the  effect  of  lowering  the  river  surface  at  a  given  point  dies  out 
rapidly  in  ascending. 

THE  LEVEE  SYSTEM. 

Levees  have  never  been  erected  upon  the  banks  of  the  Mississippi 
River  except  for  the  special  purpose  of  protecting  the  alluvial  lands 
from  overflow.  They  have,  therefore,  always  had  sole  reference  to  the 
high-water  stage,  and  the  degree  to  which  levees  might  prudently  be 
r/  relied  upon  “  to  improve  and  give  safety  to  navigation,”  “  promote  and 
facilitate  commerce,  trade,  and  the  postal  service,”  has  not  hitherto  eu- 


) 


14 


REPORT  OF  MISSISSIPPI  RIVER  COMMISSION. 


tered  into  the  question  of  the  construction  and  maintenance  of  a  levee 
system. 

There  is  no  doubt  that  the  levees  exert  a  direct  action  in  deepening 
the  channel  and  enlarging  the  bed  of  the  river  during  those  periods  of 
“  rise  ”  or  “  flood  ”  when  by  preventing  the  dispersion  of  the  flood-waters 
over  the  adjacent  low-lands,  either  over  the  river  banks  or  through  bay¬ 
ous  and  other  openings,  they  actually  cause  the  water  to  rise  to  a  higher 
level  within  the  river-bed  than  it  would  attain  if  not  thus  restrained. 

It  would  seem  to  follow,  from  the  law  that  the  volume  of  water  flow¬ 
ing  in  the  bed  determines  the  size,  that  prior  to  the  construction  of 
levees  the  area  of  the  mean  cross  section  of  bed  of  the  Mississippi  River 
must  have  been  less  than  it  was  after  the  levees  had  reached  their  most 
efficient  condition,  assuming,  what  is  believed  to  be  true,  that  the  aver¬ 
age  rainfall  iu  the  Mississippi  Valley  has  not  materially  changed  with¬ 
in  the  last  hundred  .years. 

There  is  some  evidence  in  a  comparison  of  the  results  of  Young,  Pous¬ 
sin  and  Tuttle’s  examination  of  1821,  with  later  surveys,  that  the  width 
of  the  river  has  increased  since  that  date. 

As  silt-bearing  streams  in  alluvial  districts  have  a  tendency  to  as¬ 
sume  in  the  straight  reaches  cross-sections  which  are  arcs  of  circles,  and 
in  the  bends  curves  of  deeper  forms,  it  follows  that  any  general  widen¬ 
ing  of  the  river  resulting  from  concentration  or  increase  of  volume, 
which  may  have  taken  place,  would  as  a  rule  be  accompanied  by  a  gen¬ 
eral  and  corresponding  deepening  as  the  result  of  such  general  enlarge¬ 
ment,  atthough  local  shoalings,  temporarily  injurious  to  navigation, 
might  occur. 

There  is  reason  to  believe  that  during  the  period  when  levees  were  in 
their  most  perfect  condition,  from  1850  to  1858,  the  channel  of  the  river 
was  better  generally  for  purposes  of  navigation  than  it  has  been  since 
that  time. 

It  is  known  that  during  the  last  twenty  y  ears  the  levee  system  has 
been  continuously  interrupted  by  a  great  number  of  crevasses  between 
Cairo  and  Red  River. 


Before  the  levees  were  built,  a  large  portion  of  the  flood-waters  spread 
out  over  the  banks  of  the  river  in  a  thin  sheet,  of  which  the  average 
depth  at  the  margin  of  the  stream,  where  it  escaped,  did  not  probably 
exceed  a  few  inches,  or,  at  most,  a  foot.  The  immediate  effect  of  the 
levees  would  be  to  increase  the  volume  and  height  and  accelerate  the 
velocity  of  the  flood-waters  between  them,  resulting  in  an  erosion  and 
deepening  of  the  river-bed,  and  ultimately  in  a  corresponding  lowering 
of  the  flood  slope  in  accordance  with  the  geueral  law  already  quoted, 
that  an  increase  in  the  normal  volume  of  discharge  iu  a  sedimentary 
stream,  flowing  through  alluvial  deposits,  results  ultimately  in  a  lower¬ 
ing  of  the  flood  surface.  It  would  seem,  therefore,  that  a  closure  of  the 
crevasses  might  be  expected  to  accelerate  the  removal  of  those  shoals 
which  have  been  produced  by-  them,  and  if  theirclosure  be  accompanied 
by  the  requisite  contraction  of  the  chauuel  to  a  more  nearly  uuiform 
high-water  width,  a  lowering  of  the  flood  level  may  be  expected  to  such 
extent  as  will  ultimately  render  the  maintenance  of  the  levees  as  an  aid 
to  navigation  practically  needless  above  Red  River,  and  greatly  lessen 
the  necessity  of  their  permanent  maintenance  for  that  purpose  below 
Red  River,  even  at  a  reduced  height. 

While  it  is  not  claimed  that  levees  in  themselves  are  necessary  as  a 
means  of  securing  ultimately  a  deep  channel  for  navigation,  it  is  believed 
that  the  repair  and  maintenance  of  the  extensive  lines  already  existing 
will  hasten  the  work  of  channel  improvement  through  the  increased 


REPORT  OF  MISSISSIPPI  RIVER  COMMISSION 


15 


scour  and  depth  of  river-bed  which  they  would  produce  during  the  high- 
river  stages.  They  are  regarded  as  a  desirable,  though  not  a  necessary, 
adjunct  in  the  general  system  of  improvement  submitted. 

It  is  obvious  that  levees  are,  upon  a  large  portion  of  the  river,  essen¬ 
tial  to  prevent  destruction  to  life  and  property  by  overflow.  They  give 
safety  and  ease  to  navigation  and  promote  and  facilitate  commerce  and 
trade  by  establishing  banks  or  landing  places  above  the  reach  of  floods, 
upon  which  produce  can  be  placed  while  awaiting  shipment,  and  where 
steamboats  and  other  river  craft  can  laud  in  times  of  high  water. 

In  a  restricted  sense  as  auxiliary  to  a  plan  of  channel  improvement 
only,  the  construction  and  maintenance  of  a  levee  system  is  not  de¬ 
manded.  But  in  a  larger  sense,  as  embracing  not  only  beneficial  effects 
upon  the  channel,  but  as  a  protection  against  destructive  floods,  a  levee 
system  is  essential ;  and  such  system  also  promotes  and  facilitates  com¬ 
merce,  trade,  and  the  postal  service. 

A  levee  system  aids  and  facilitates  the  postal  service  by  protecting 
from  injury  and  destruction  by  freshets  and  floods  the  various  common 
roads  and  railways  upon  which  that  service  is  conducted  to  and  from 
the  river  bank,  and  generally  within  that  portion  of  the  alluvial  region 
subject  to  overflow.  Moreover,  the  permanent  maintenance  below  Cairo 
of  a  connected  levee  system,  a  system  of  sufficient  strength  to  inspire 
confidence  in  its  efficiency,  or  the  demonstration,  by  the  achieved  results 
of  an  improved  river,  that  overflow  need  no  longer  be  seriously  appre¬ 
hended,  would  act  as  a  prompt  and  powerful  stimulant  in  rapidly  de¬ 
veloping  a  largely  increased  trade  and  commerce  in  all  the  products  of 
agricultural  industry  indigenous  to  that  region,  and  in  those  branches 
of  manufacturing  enterprise  related  thereto. 

The  foreging  is  submitted  as  the  opinions  of  this  Commission,  with  re¬ 
gard  to  the  attributes  and  functions  of  levees,  and  their  general  utility 
and  value.  The  views  of  the  several  members,  however,  are  not  in  en¬ 
tire  accord  with  respect  to  the  degree  of  importance  which  should  attach 
to  the  concentration  of  flood- waters  by  levees,  as  a  factor  in  the  plan  of 
improvement  of  low-water  navigation,  which  has  received  the  unanimous 
preference  of  the  Commission. 

The  breaks  in  the  levees  were  estimated  in  January,  1875,  by  the  com¬ 
mission  for  the  reclamation  of  the  alluvial  basin  of  the  Mississippi  River, 
to  amount  to  8,065,700  cubic  yards.  It  is  believed  that  the  repairs  done 
in  Louisiana  and  Mississippi  siuce  that  time  will  fully  equal  the  enlarg- 
rnent  of  the  openings  in  Arkansas  and  Missouri.  The  estimate  of  the 
cost  of  closing  the  breaks  in  the  existing  system  of  levees  to  the  former 
height  is  based  upon  this  hypothesis. 

The  want  of  completed  surveys  and  the  limited  su pi )ly^  of  labor  would 
render  diffirult  the  construction  of  more  than  one-half  of  this  amount 
of  work  in  any  one  year. 


Estimate  of  cost. 

For  closing  to  their  former  height  the  gaps  in  the  existing  levees  between 
Cairo  and  New  Orleans,  8,065,700  cubic  yards  of  earthwork,  at  23  cents 


per  yard .  $1,855,111 

Add  for  contingencies .  164,889 

Total  for  repairs  of  existing  levees .  $2,  020,  000 


This  does  not  include  the  cost  of  maintenance,  for  which  no  reliable 
estimate  can  be  made  in  the  absence  of  data  giving  the  required  dimen¬ 
sions'  of  the  levees  and  their  positions  relative  to  caving  banks.  For 
the  absolute  prevention  of  destructive  floods,  the  former  height  of  the 


16 


REPORT  OF  MISSISSIPPI  RIVER  COMMISSION. 


levees  would  have  to  be  increased,  but  no  exact  estimate  of  the  cost  of 
these  higher  levees  can  be  made  at  present  for  want  of  the  necessary 
data. 


PLAN  OF.  IMPROVEMENT  RECOMMENDED. 

The  bad  navigation  of  the  river  is  produced  by  the  caviug  and  ero¬ 
sion  of  its  banks,  and  the  excessive  widths  and  the  bars  and  shoals 
resulting  directly  therefrom. 

It  has  been  observed  in  the  Mississippi  River,  and  is  indeed  true  of 
all  siltbearing  streams  flowing  through  alluvial  deposits,  that  the 
more  nearly  the  high  river  width,  or  width  between  the  banks,  ap¬ 
proaches  to  uniformity,  the  more  nearly  uniform  will  be  the  channel 
depth,  the  less  will  be  the  variations  of  velocity,  and  the  less  the  rate 
of  caving  to  be  expected  in  concave  bends.  This  would  seem  to  be  so 
in  the  very  nature  of  things,  because  uniformity  of  width  secured  by 
eontraction  will  produce  increased  velocity,  and  therefore  increased 
erosion  of  bed  at  the  shoal  places,  accompanied  by  a  corresponding  de¬ 
posit  of  silt  at  the  deep  places,  and  consequently  greater  uniformity  of 
depth. 

Uniform  depth  joined  to  uniform  width,  that  is  to  say,  uniformity  of 
effective  cross  section,  implies  uniform  velocity,  aud  this  means  that 
there  will  be  no  violent  eddies  and  cross  currents,  and  no  great  aud  sud¬ 
den  fluctuations  in  the  silt-transporting  power  of  the  current.  There  will 
therefore  be  less  erosion  from  oblique  currents  and  eddies,  aud  no  form¬ 
ations  of  shoals  and  bars  produced  by  silt  taken  up  from  one  part  of  the 
chaunel  aud  dropped  in  another.  As  the  friction  of  the  bed  retards  the 
flow  of  the  water,  any  diminution  of  the  friction  will  promote  the  discharge 
of  floods.  The  frictional  surface  is  greater  in  proportion  to  volume  of 
discharge  where  the  river  is  wide  and  shoal  than  where  it  is  narrow  aud 
deep.  It  follows,  therefore,  that  after  the  wide  shoal  places  are  suitably 
narrowed,  aud  the  normal  sectional  area  is  restored  by  deepening  the 
channel,  the  friction  will  be  less  than  it  was  before.  This  will  result  in 
a  more  easy  and  rapid  discharge  of  the  flowing  water,  aud  consequently 
in  a  lowering  of  the  flood-surface.  It  would  seem,  therefore,  that  the 
plan  of  improvement  must  comprise,  as  its  essential  features,  the  con¬ 
traction  of  the  water-way  of  the  river  to  a  comparatively  uniform  width, 
and  the  protection  of  caving  banks,  and  this  is  presumed  to  be  the  plan 
referred  to  in  the  act  as  the  “jetty  system.”  It  is  known,  from  observa¬ 
tion  of  the  river  below  Cairo,  not  only  that  shoals  and  bars,  producing 
insufficient  depth  and  bad  navigation,  are  always  accompanied  by  a 
low-water  width  exceeding  3,01)0  feet,  but  that  wherever  the  river  does 
not  exceed  that  width  there  is  a  good  channel  In  other  words,  bad 
navigation  invariably  accompanies  a  wide  low-river  water-way,  and 
good  navigation  a  narrow  one. 

The  work  to  be  done,  therefore,  is  to  scour  out  aud  maintain  a  chau¬ 
nel  through  the  shoals  and  bars  existing  in  those  portions  of  the  river  , 
where  the  width  is  excessive,  and  to  build  up  new  banks  and  develop 
new  shore  lines,  so  as  to  establish  as  far  as  practicable  the  requisite 
conditions  of  uniform  velocity  for  all  stages  of  the  river. 

It  is  believed  that  this  improvement  can  be  accomplished  below  Cairo 
by  contracting  the  low-water  channel-way  to  an  approximately  uniform 
width  of  about  3,000  feet,  for  the  purpose  of  scouring  out  a  channel 
through  the  shoals  and  bars,  and  by  causing,  through  the  action  of  ap¬ 
propriate  works  constructed  at  suitable  localities,  the  deposition  of  sand 
aud  other  earthy  materials  transported  by  the  water  upon  the  dry  bars 


REPORT  OF  MISSISSIPPI  RIVER  COMMISSION. 


17 


and  other  portions  of  the  present  bed  not  embraced  within  the  limits  of 

r  the  proposed  low-water  channel.  The  ultimate  effect  sought  to  be  pro- 

*  duced  by  such  deposits  is  a  comparative  uniformity  in  the  width  of  the 
high-water  channel  of  the  river. 

It  is  believed  that  the  works  estimated  for  in  this  report  will  create 
Jfj  x  and  establish  a  depth  of  at  least  10  feet  at  extreme  low  stages  of  the 
\  river  over  all  the  bars  below  Cairo,  where  they  are  located. 

It  is  the  opinion  of  this  Commission  that,  as  a  general  rule,  the  chan¬ 
nel  should  be  fixed  and  maintained  in  its  present  location ;  and  that  no 
attempt  should  be  made  to  straighten  the  river  or  to  shorten  it  by  cut¬ 
offs. 

The  borings  which  were  made  in  1879  at  New  Madrid  and  Plum 
Point,  by  direction  of  the  Board  of  Engineers  for  the  improvement  of  the 
low-water  navigation  of  the  Mississippi  River  below  Cairo,  and  those  of 
more  recent  date  at  Memphis  and  Helena,  made  under  the  orders  of 
this  Commission,  as  well  as  those  near  Lake  Borgue,  reported  by  the 
levee  commission  of  1875,  and  others  made  along  the  proposed  line  of 
the  Fort  Saint  Philip  Canal,  and  the  artesian  well  sunk  at  New  Orleans, 
all  furnish  concurrent  evidence  of  the  yielding  character  of  the  strata 
forming  the  river-bed.  This  evidence,  taken  in  connection  with  the  fact 
that  deep  water  is  found  in  all  the  bends  of  the  river  where  the  width 
is  not  excessive,  and  that  these  bends  have,  by  their  shiftings  at  one 
time  or  another,  probably  occupied  and  covered  nearly  every  part  of  the 
belt  from  10  to  20  miles  in  width  from  Cairo  to  the  Gulf,  point  to 
the  conclusion,  if  it  does  not  indeed  justify  it,  that  there  is  no  extensive 
stratum  of  material  capable  of  resisting  erosion  and  preventing  the 
/  river  from  deepening  its  own  bed.  In  exceptional  localities,  where  the 

.a  material  is  too  tough,  or  the  gravel  too  heavy  for  removal  by  scour, 

*  dredging  may  have  to  be  resorted  to  as  an  auxiliary,  the  depth  secured 
by  this  means  being  maintained  by  the  works  erected  for  narrowing  the 
stream. 

>  Experience,  as  well  in  this  country  as  in  Europe,  justifies  the  belief 
that  the  requisite  correction  and  equalization  of  the  transverse  profile 
of  the  stream,  by  developing  new  shore-lines  andbuilding  up  new  banks, 
may  be  made  chiefly  through  the  instrumentalities  of  light,  flexible,  and 
comparatively  inexpensive  constructions  of  poles  and  brush,  and  mater¬ 
ials  of  like  character.  These  constructions  will  commonly  be  open  or 
permeable  to  such  degree  that,  without  too- violently  arresting  the  flow 
of  water,  thereby  unduly  increasing  the  head  and  causing  dangerous 
underscour,  they  will  sufficiently  check  the  current  to  induce  a  deposit 
of  silt  in  selected  localities. 

The  works  which  have  been  used  in  similar  improvements  are  of  vari¬ 
ous  forms  and  devices,  such  as  the  hurdle,  composed  of  a  line  of  stakes 
or  light  piles,  with  brush  interlaced ;  the  open  dike,  formed  of  stakes 
with  waling  strips  on  both  sides  filled  in  loosely  with  brush  ;  the  con¬ 
tinuous  brush  mattress,  built  or  woven  on  fixed  or  floating  ways  and 
f  '  launched  as  fast  as  completed,  as  a  revetment  to  a  caving  bank,  the 

mattress  used  as  a  vertical  or  inclined  curtain,  placed  in  the  stream  to 
check  the  current,  the  same  laid  flat  on  the  bottom  as  the  foundation 
for  such  a  curtain  or  as  an  anchorage  for  other  brush  devices  ;  curtains 
of  wire  or  brush  netting,  placed  vertically  or  inclined  in  the  stream  ; 
and  various  other  forms  of  permeable  brush  dikes,  jetties,  or  revetments. 
Some  of  these  methods  of  construction  have  been  used  on  the  Missis- 

*  sippi  and  Missouri  rivers  with  increasing  satisfaction  and  success, 
although  they  cannot  yet  be  regarded  as  entirely  beyond  the  experi¬ 
mental  stage."  In  some,  perhaps  in  many  localities,  works  of  a  much  more 

5  solid  character  than  those  above  indicated  may  be  necessary. 

H.  Ex.  58 - 2 


18 


REPORT  OF  MISSISSIPPI  RIVER  COMMISSION. 


The  closure  of  deep  channels  or  low-water  chutes,  with  a  view  of  con¬ 
fining  the  flow  to  a  single  passage,  may  require  substantial  dams  of 
brush  and  riprap  stone  or  gravel,  but  it  is  believed  the  lighter  and  less 
costly  works  will  generally  suffice. 

By  a  permeable  dike  located  upon  the  new  shore-line  to  be  developed, 
connected  with  the  old  bank  at  suitable  intervals  by  cross  lines  of  like 
character,  or  by  jetties  of  hurdles  or  other  permeable  works  projecting 
from  the  bank  with  their  channel  ends  terminating  on  the  margin  of 
the  proposed  water  way,  or  by  any  other  equivalent  works,  the  area  to 
be  reclaimed  and  raised  will  be  converted  into  a  series  of  silting  basins, 
from  which  the  water,  flowing  through  the  barriers  with  diminished 
velocity,  will,  after  depositing  its  heavier  material,  pass  off  and  give 
place  to  a  new  supply.  In  this  manner  the  accretion  will  go  on  contin¬ 
uously  through  the  high-water  season,  or  through  two  or  more  seasons 
if  necessary,  the  works  being  renewed  on  the  higher  level  as  occasion 
requires. 

Wherever  necessary,  the  new  bank  must  be  protected  by  a  mattress, 
revetment,  or  some  equivalent  device. 

That  these  methods  of  improvement  are  practicable,  is  shown  by  the 
works  already  executed  on  the  Mississippi  and  Missouri  rivers. 

The  plan  submitted  by  the  Board  of  Engineers  for  the  improvement 
of  the  low-water  navigation  of  the  river  below  Cairo,  in  their  report  dated 
January  25,  1879  (see  House  Ex.  Doc.  No.  41,  Forty-fifth  Congress, 
third  session,)  in  which  it  is  recommended  that  $009,000  be  asked  for 
the  improvement  of  the  Plum  Point  Beach,  and  u  that  the  improve¬ 
ment  be  effected  by  narrowing  the  shoal  and  wide  portions  of  the  low- 
water  river  to  about  3,500  feet,  and  by  protecting  caving  banks  where 
necessary,77  is  substantially  adopted  for  the  initial  works  submitted  for 
construction  in  this  report. 

An  accurate  estimate  of  the  cost  of  properly  improving  the  entire  river 
below  Cairo  cannot  be  made  until  after  the  completion  of  the  surveys 
now  in  progress.  Moreover,  estimates  based  upon  the  latest  data  from 
those  surveys  will  doubtless  require  modification  in  some  particulars,  to 
meet  subsequent  changes  in  the  river,  and  will  perhaps  be  considerably 
reduced  in  the  aggregate  amount  by  improved  methods  of  construction 
developed  during  the  progress  of  the  wrork. 

INITIAL  WORKS. 

Under  the  authority  conferred  in  section  5  of  the  act,  estimates  of 
cost  of  certain  initial  works,  constituting  a  component  part  of  the  gen¬ 
eral  system  of  wrorks  contemplated,  are  submitted. 

Those  works  of  channel  contraction  and  bank  protection,  which  in  the 
judgment  of  this  Commission  may  be  advantageously  undertaken  dur¬ 
ing  the  coming  fiscal  year  or  as  soon  as  Congress  supplies  the 
means,  are  confined  to  an  aggregate  length  of  nearly  200  miles  of  the 
shoalest  water  below  Cairo,  embracing  the  following  localities,  viz  : 
NewT  Madrid,  Plum  Point,  Memphis,  Helena,  Choctaw  Bend,  and  Lake 
Providence. 

The  estimates  are  intended  to  cover  the  cost  of  works  for  contracting 
the  channel  and  for  securing  and  protecting  the  banks;  for  the  neces¬ 
sary  outfit  of  boats,  tugs,  tools,  &c.,  to  carry  on  the  work  for  local  sur¬ 
veys,  the  salaries  of  engineers,  superintendents,  and  inspectors,  and  the 
necessary  office  expenses.  Further  appropriations  will  be  needed  to 
complete  the  works,  secure  their  permanence,  and  develop  the  full  bene¬ 
fit  of  the  system. 


REPORT  OF  MISSISSIPPI  RIVER  COMMISSION. 


19 


As  regards  the  final  cost,  the  novelty  of  the  devices  to  be  employed 
and  the  absence  of  experience  with  respect  to  the  rapidity  and  degree 
of  their  results,  forbid  any  exact  estimate  $  but  it  is  believed  that  such 
additional  works  as  will  ultimately  be  required  to  complete  and  render 
permanent  the  improvement  contemplated  in  this  system  at  the  locali¬ 
ties  specified  will  not  exceed  the  amount  hereinbelow  stated  as  needed 
for  initial  works. 

It  is  considered  necessary  that  a  contingent  sum,  which  is  inserted  in 
the  estimates  lor  initial  work,  be  appropriated  for  use  in  any  emergency 
that  may  arise  for  securing  or  protecting  the  works  at  any  point  after 


the  specific  appropriation  may  have  been  exhausted. 

Estimates. 

New  Madrid  Reach,  40  miles  long: 

Works  for  contracting  the  channel  and  protecting  the  banks .  $776,  000 

For  outfit,  superitendence,  inspection,  office  expenses,  and  local  surveys....  147,  000 

Total  for  New  Madrid  Reach . '. .  $92,  3000 

Plum  Point  Reach,  38  miles  long  : 

Works  for  contracting  the  channel  and  protecting  the  hanks .  599,  000 

For  outfit,  superintendence,  inspection,  office  expenses,  and  local  surveys.. .  137,  000 

Total  for  Plum  Point  Reach . ' .  $736,  000 

Memphis  Reach,  16  miles  long: 

Works  for  contracting  the  channel  and  protecting  the  hanks .  282,  000 

For  outfit,  superintendence,  inspection,  office  expenses,  and  local  surveys  ..  100,  000 

Total  for  Memphis  Reach .  $382, 000 

Helena  Reach,  30  miles  long: 

Works  for  contracting  the  channel  and  protecting  the  hanks .  $515,  000 

For  outfit,  superintendence,  inspection,  office  expenses,  and  local  surveys.. .  112,  000 

Total  for  Helena  Reach  . . . .  $627,  000 

Choctaw  Bend,  35  miles  long  : 

Works  for  contracting  the  channel  and  protecting  the  hanks .  464,  000 

For  outfit,  superintendence,  inspection,  office  expenses,  and  surveys .  112,000 

Total  for  Choctaw  Bend .  $576,000 

Lake  Providence  Reach,  25  miles  long  : 

Works  for  contracting  the  channel  and  protecting  the  hanks .  507,  000 

For  outfit,  superintendence,  inspection,  office  expenses,  and  local  surveys.. .  112,  000 

Total  for  Providence  Reach . $619,000 

Contingencies.. . $250,000 


Should  it  be  determined  not  to  appropriate  the  amounts  estimated  for 
all  the  initial  works,  it  is  considered  important  that  the  reduction  should 
be  made  rather  in  the  number  of  places  at  which  work  is  proposed  than 
by  reducing  the  estimates  for  any  one  place. 

Estimates  for  ivories  of  improvement  for  the  first  fiscal  year. 


Initial  works  for  channel  contraction  and  hank  protection  . .  $4, 113,  000 

Closing  gaps  in  levees .  1,010,000 

Checking  enlargement  of  Atcliafalaya .  10,  000 

e 

Estimates  for  surveys  and  for  expenses  of  Commission  for  fiscal  year  ending  June  30, 1881. 

For  surveys  and  examinations  above  and  below  Cairo,  and  the  necessary 

salaries  and  other  expenses  of  the  Mississippi  River  commission .  $200,  000 


20 


REPORT  OF  MISSISSIPPI  RIVER  COMMISSION. 


If  Congress  shall  authorize  any  extensive  works  of  improvement  on 
the  Mississippi,  we  would  respectfully  suggest  that  provision  be  made 
by  law  for  the  appropriation  of  such  land  and  materials  as  may  be  needed 
in  the  work  when  the  same  cannot  be  obtained  upon  equitable  terms  by 
purchase  from  the  owner.  We  do  not  contemplate  that  a  resort  to  such 
proceedings  would  often  be  necessary ;  but  in  the  absence  of  any  such 
provision  of  law,  individual  owners  of  the  property  required  might 
greatly  and  unjustly  enhance  the  cost  of  the  work. 

Authority  to  file  in  the  proper  court' of  the  United  States  an  article 
of  appropriation  describing  the  property  to  be  taken,  and  to  have  an 
assessment  by  competent  appraisers  of  its  value,  would  tend  to  prevent 
extortion,  and  at  the  same  time  secure  to  the  individual  a  just  recom¬ 
pense  for  the  property  taken. 

We  venture  to  suggest  further  that  in  case  the  Commission  should 
be  continued  in  existence  and  the  works  recommended  by  it  be  in  whole 
or  in  part  authorized  by  Congress,  the  execution  of  the  work  and  the 
expenditure  of  the  appropriations  therefor  shall  not  be  made  part  of  the 
duty  of  the  Commission.  We  think  the  duties  of  the  Commission  should 
be  limited  to  the  preparation  of  plans,  their  modification  when  neces¬ 
sary,  the  advisory  supervision  of  the  work,  and  the  completion  of  the 
surveys  and  observations.  This  would  secure  unity  of  plan,  greater 
efficiency  in  the  work,  and  a  better  system  of  checks  upon  the  expen¬ 
ditures  than  we  could  hope  to  secure  if  the  entire  work  of  devising, 
executing,  and  disbursing  were  cast  upon  the  Commission. 

All  of  which  is  respectfully  submitted. 

Q.  A.  GILLMORE, 

Lieutenant- Colonel  of  Engineers ,  Bvt.  Maj.  Gen ., 

President  Mississippi  River  Commission. 

CHAS.  R.  SUTER, 

Major  of  Engineers ,  U.  S.  A. 

HENRY  MITCHELL, 

Coast  and  Geodetic  Survey. 

JAS.  B.  EADS. 

B.  M.  HARROD. 

Hon.  Alexander  Ramsey, 

Secretary  of  War ,  Washington ,  D.  C. 


APPENDIX  1. 

Washington,  D.  C.  February  16,  1880. 
Financial  statement. 

Amount  appropriated  for  expenses  of  tlie  Mississippi  River 

Commission,  by  act  approved  June  28,  1879 .  $175,  000  00 

Amount  expended  to  February  16,  1880,  including  outstanding  lia¬ 
bilities  : 

For  surveys  and  observations .  f 65, 691  21 

For  salaries  of  Commissioners .  5,024  99 

For  mileage  and  inspection .  '8,167  88 

For  reduction  of  maps .  1,920  70 

For  office  expenses .  4, 195  22 

Balance  which  it  is  estimated  will  be  required  during  remain¬ 
der  of  the  fiscal  year  ending  June  30,  1880 .  90,  000  00 

-  175,000  00 

SMITH  S.  LEACH, 

First  Lieutenant  of  Engineers ,  U.  S.  A., 
Secretary  Missouri  River  Commission. 


REPORT  OF  MISSISSIPPI  RIYER  COMMISSION. 


21 


The  Mississippi  River  Commission, 
j  President’s  Office,  Army  Building, 

*  33  West  Houston  Street, 

New  Yorlc,  March  8,  1880. 

Sir  :  I  have  the  honor  to  transmit  herewith  the  minority  report  of 
T  General  Comstock  and  Mr.  Harrison,  to  be  attached  to  the  report  of 
the  Mississippi  River  Commission  forwarded  with  rn.y  letter  of  the  6th 
instant. 

Very  respectfully,  your  obedient  servant, 

Q.  A.  GILLMORE, 

Lieutenant- Colonel  of  Engineers,  IPvH  Maj.  Gen .,  JJ.  S  A., 

President  Mississippi  River  Commission . 
Hon.  Alexander  Ramsey, 

Secretary  of  War ,  Washington ,  T>.  C. 

[Indorsement.] 

Office  Chief  of  Engineers,  U.  S.  Army, 

March  9,  1880. 

Respectfully  forwarded  to  the  honorable  the  Secretary  of  War,  to  ac¬ 
company  report  of  Mississippi  River  Commission  transmitted  on  the  8th 
instant. 

H.  G.  WRIGHT, 

Chief  of  Engineers ,  Brig.  &  Bt.  Maj.  Gen. 


MINORITY  REPORT. 

While  of  the  opinion  that  an  ample  depth  of  water  for  navigation  on 
^  the  Mississippi  River  below  Cairo  can  be  obtained  by  contraction  of  the 
low-water  width  at  shoal  places  to  about  3,000  feet,  erosion  being  aided 
by  dredging  if  necessary ;  and  while  of  the  opinion  that  levees  are  es¬ 
sential  to  prevent  injury  to  alluvial  lands  by  destructive  floods,  and  that 
outlets  should  not  in  general  be  used,  there  are  some  less  important 
points  on  which  we  do  not  concur  in  the  views  of  the  majority  of  the 
Commission. 

1.  WTe  caunot  concur  in  the  unqualified  form  of  expression  of  certain 
theoretical  views,  believing  them  to  have  too  many  exceptions  to  furnish 
safe  bases  for  practical  conclusions.  One  such  statement  is  : 

If  the  normal  volume  of  water  in  a  silt-bearing  stream,  flowing  in  an  alluvial  bed  of 
its  own  formation,  be  permanently  increased,  there  will  result  *  *  *  ultimately 

a  lowering  of  the  surface  slope. 

While  this  statement  and  its  converse  are  usually  true,  they  yet  omit 
some  factors  which  influence  the  relation  between  discharge  and  slope. 
One  is  the  coarseness  and  quantity  of  the  sediment  which  the  increase 
of  volume  brings ;  another  is  the  ratio  of  flood  to  low-water  discharge ; 
and  another  the  varying  coarseness  of  the  material  forming  the  bed  of 
the  river  at  the  same  place  at  different  times  or  at  different  places. 

When  the  increase  of  volume  brings  with  it  much  coarse  sediment, 
the  slope  may  be  increased  instead  of  diminished,  by  increase  of  volume. 

^  This  effect  has  been  frequently  observed  below  the  mouths  of  tribu¬ 
taries. 

Again,  if  the  ratio  of  flood  to  low- water  discharge  could  be  made  to 


f 


22 


REPORT  OF  MISSISSIPPI  RIVER  COMMISSION. 


approach  unity,  the  annual  discharge  remaining  unchanged,  it  is  prob¬ 
able  that  the  middle  Mississippi  would  have  a  smaller  slope  than  at 
present,  approaching  that  of  the  river  below  New  Orleans,  where  the 
flood  rise  is  small.  In  that  case  the  annual  discharge  might  be  dimin¬ 
ished  without  increasing  the  slope  beyond  its  present  value. 

2.  We  do  not  concur  with  the  majority  of  the  Commission  in  their 
estimate  of  the  value  of  the  closure  of  gaps  in  existing  levees  as  a 
factor  in  the  improvement  of  low-water  navigation  ;  this  estimate  being 
derived  in  part  from  the  theoretical  views  already  referred  to. 

Existing  evidence  seems  to  show  that  during  low-water  stages  the 
bars  below  Cairo  are  usually  cut  out  by  the  river,  and  that  when  the 
period  of  low  river  in  the  following  season  approaches,  these  low- water 
channels  are  found  filled  up,  the  low-water  lied  of  the  river  in  these 
shoal  places  having  risen,  to  be  again  cut  out  by  the  low  river.  (See 
Major  Suter’s  report  in  Report  of  Chief  Engineers,  1875.) 

At  the  Horse  Tail  Bar,  below  Saint  Louis,  the  bed  of  the  river  has 
been  observed  to  rise  8  or  10  feet  above  low-water  in  the  interval  be¬ 
tween  two  low-river  periods.  (See  General  Simpson’s  report  in  Chief 
of  Engineer’s  report,  1876.) 

If,  then,  the  final  effect  of  a  flood  which  rises  from  30  to  50  feet 
above  low-water  is  to  raise  the  low-water  bed  of  the  river  at  shoal 
places,  may  it  not  be  possible  that  if  the  height  of  this  flood  be  some¬ 
what  increased  by  levees  the  bed  may  rise  still  further  instead  of  being 
depressed,  thus  injuring  instead  of  improving  navigation  ? 

But  even  if  a  rise  or  fall  of  a  foot  or  two  in  the  bed  of  the  river  were 
produced  by  levees,  it  is  difficult  to  see  how  this  would  sensibly  affect 
the  low-water  width  of  the  river.  Bad  navigation  arises  from  excessive 
low-water  width  at  certain  places,  and  is  to  be  cured  by  contracting 
that  low-water  width  to  about  3,000  feet.  This  contraction  must  be 
effected  by  works  in  the  bed  of  the  river,  and  not  by  levees  on  top  of 
its  banks,  out  of  contact  with  the  low-water  river. 

For  these  reasons  we  are  of  the  opinion  that  levees  are  of  very  little 
value  in  improving  the  low-water  navigation  of  the  river.  Of  their 
necessity  in  protecting  alluvial  lauds  against  destructive  floods  there 
can  be  no  doubt,  and  to  obtain  such  protection  the  first  step  would  be 
the  closure  of  gaps  in  existing  levees.  The  regulation  of  the  low-water 
river,  including  the  fixation  of  the  river  banks,  would  be  of  the  great¬ 
est  aid  to  the  levees,  since  it  would  secure  them  from  destruction  by 
caving. 

The  majority  report  anticipates  as  a  result  of  the  proposed  works  a 
lowering  of  the  flood-level  to  such  an  extent  “  as  will  ultimately  render 
the  maintenance  of  the  levees  as  an  aid  to  navigation  practically  need¬ 
less  above  Red  River.” 

As  to  the  larger  question,  whether  the  proposed  works  will  make 
levees  unnecessary  to  prevent  destructive  floods  on  this  part  of  the 
river,  there  are  in  our  opinion  no  sufficient  data  for  drawing  reliable 
conclusions ;  theoretically  they  should  in  some  degree  lower  the  bed. 

A  reduction  of  the  flood-level  is  very  desirable,  but  where  on  other 
rivers  this  has  been  effected,  cut-offs  have  usually  played  an  essential 
part.  For  this  reason  we  are  not  prepared  to  absolutely  reject  their 
use,  after  the  banks  of  the  river  have  been  thoroughly  protected  for 
considerable  distances  above  and  below  the  sites  where  they  are  about 
to  occur. 

3.  From  the  lack  of  sufficient  experience,  either  in  this  country  or 
abroad,  in  the  improvement  of  rivers  by  the  means  recommended  in  the 
report,  the  estimates  of  cost  can  only  be  considered  as  rough  approxi- 


REPORT  OF  MISSISSIPPI  RIVER  COMMISSION.  23 

mations,  since  the  strength  needed  for  the  works  will  have  to  be  de¬ 
termined  by  trial.  For  this  reason  we  think  it  in  the  interest  of  economy 
that  works  should  not  in  the  first  year  be  undertaken  at  more  than  one 
or  two  of  the  points  for  which  estimates  are  submitted. 

C.  B.  COMSTOCK, 

Major  of  Engineers  and  Bvt.  Brig.  Gen. 

BENJAMIN  HABKISON. 


. 


) 


